The fabrication of an integrated circuit, display or disc memory generally employs numerous processing steps. Each process step must be carefully monitored in order to provide an operational device. Throughout the imaging process, deposition and growth process, etching and masking process, etc., it is critical, for example, that temperature, gas flow, vacuum pressure, chemical gas or plasma composition and exposure distance be carefully controlled during each step. Careful attention to the various processing conditions involved in each step is a requirement of optimal semiconductor or thin film processes. Any deviation from optimal processing conditions may cause the ensuing integrated circuit or device to perform at a substandard level or, worse yet, fail completely.
Within a processing chamber, processing conditions vary. The variations in processing conditions such as temperature, gas flow rate and/or gas composition greatly affect the formation and thus the performance of the integrated circuit. Using a substrate-like device to measure the processing conditions that is of the same or similar material as the integrated circuit or other device provides the most accurate measure of the conditions because the thermal conductivity of the substrate is the same as the actual circuits that will be processed. Gradients and variations exist throughout the chamber for virtually all process conditions. These gradients therefore also exist across the surface of a substrate. In order to precisely control processing conditions at the substrate, it is critical that measurements be taken upon the substrate and that the readings are available to an automated control system or operator so that the optimization of the chamber processing conditions can be readily achieved. Processing conditions include any parameter used to control semiconductor or other device manufacture or any condition a manufacturer would desire to monitor.
U.S. Pat. No. 6,691,068 to Freed et al. teaches a sensor apparatus capable of measuring data, processing data, storing data, and transmitting data for a process tool used for processing workpieces. The sensor apparatus includes an information processor, embedded executable commands for controlling the apparatus, and at least one sensor. The sensor apparatus is capable of being loaded into a process tool. The sensor apparatus has capabilities for near real time data collection and communication.
Conventionally, the low profile wireless measurement device is mounted on the substrate to measure the processing conditions. For a low profile wireless measurement device to work in a high temperature environment (e.g., temperatures greater than about 150° C.), certain key components of the device, such as thin batteries and microprocessors, must be able to function when the device is exposed to the high temperature environment. Conventionally, the back AR coating (BARC) process operates at 250° C.; a CVD process may operate at a temperature of about 500° C.; and a PVD process may operate at about 300° C. Unfortunately, many types of battery, for example thin film Li batteries, melt at 180° C. The battery packaging materials may outgas at 180° C. also causing battery damage.
To build a high temperature (150° C. and higher) version of a wireless temperature measurement device, certain components that are commercially available have limited ability to operate at high temperatures. Furthermore, components with sufficient high temperature capability are not likely to be commercially available in the near future. A further challenge is that, in addition to being insulated against heat transfer, the battery should keep a profile of 2 mm or less in the wireless measurement device in order to fit into various process chambers.
It is within this context that embodiments of the present invention arise.